Fire extinguishing composition



Patented Get. 330, 1%45 FIRE EX'llNGUlISc: 9* G cormosrrron Robert E.Sargent and Matthew W. M. Dewitt, Elmhurst, Long Island, N. 2!.

No Drawing. Application April 4%, 1942, Serial No. 437,694

3 Claims.

The instant invention relates to a composition of matter and moreparticularly to a composition for extinguishing fires not readilyextinguished by ordinary methods, such as water under pressure. Moreparticularly, the invention is concerned with a composition of matterfor use in extinguishing fires of a type which are not extinguished byordinary methods, but in which the rate of combustion is, in fact,accelerated by such methods.

One of the primary objects of the invention, therefore, is the making ofa composition of matter which will function to emciently extinguish astubborn fire produced by incendiary bombs and the ignition of readilyignitable materials, such as magnesium in all its forms, among which maybe mentioned solid magnesium, magnesium chips, turnings and ribbons,magnesium alloys, also metallic paint powders generally, aluminum chipsand powders, sodium and phosphorus fires and the like.

It is readily agreed by experts in the fire fighting field that the mostefiicient manner of extinguishing fires of the character referred toabove is based on sufiocationand it is, therefore, one of the primarypurposes of this invention to make a composition of matter which willaccomplish this result quickly and efficiently.

Still another aim of the invention is a composition of matter includingingredients which are readily available and of low cost.

In fires of the character described above, it is frequentlyrecommended'that dry sand be used to sufiocate the same and to confinethe ignited material to a limited area. While this is good as far as itgoes, there is a definite limitation to its use which may be in partexplained as follows. Ordinary sand is composed of a large number ofindividual sharp grains of silica and it is diificult, therefore, toform an impervious oxygenexcluding layer over the aforementioned ignitedmaterials. Accordingly, it will be understood that oxygen from the airin some quantities will find access to the burning materials and,therefore, aid or accelerate the combustion thereof, thus prolonging theburning time. It is consequently a further purpose of the composition ofthe instant invention to function well without handicap of thecharacteristic connected with the use of sand as a suffocating agent.

Set out below are the ingredients which I have found to be best suitedfor the purposes hereinbei'ore mentioned, the proportions being giveninapproximate parts by weight:

Ounces Sodium chloride 704 Finely divided pitch 20 Graphite 16 Theprincipal ingredient of the composition, as

will be noted, is sodium chloride. This ingredient performs a pluralityof functions in the use of the composition. First, it serves as anexcellent conductor of heat and operates to remove the heat from theburning mass. Secondly, the

great heat liberated by burning materials of the type set out above willdecompose the sodium chloride with the liberation of chlorine gas, thelatter operating as a suffocating blanket over the fire excluding oxygentherefrom. As is well known, chlorine gas itself is not a supporter ofcombustion. The pitch acts as a binder, serving to unite the crystals ofsodium chloride. Thus, when the product, containing the pitch as abinder, i s applied to a burning mass, the heat melts the pitch andcauses the intergranular spaces in the sodium chloride to becomethoroughly filled or plugged up by said melted pitch, so that in the useof the composition an impervious mass of material will cover the burningmaterials. In this manner the drawback in the use of ordinary dry sand,as explained hereabove, will be obviated.

The graphite acts as a lubricant in the use of the composition and isparticularly valuable when the composition is employed in the vicinityof machinery, particularly machinery upon which metallic magnesium orthe like is being processed with the formation of magnesium chips,ribbons or powders.

Finally, the graphite will coat the surface of each grain of sodiumchloride serving to inhibit the normal absorption of moisture from theair by the salt. The value of this property is enhanced when ordinarycommercial salt is employed. As will be understood, the commercialproduct is apt to contain relatively large quantities of hygroscopicmaterials, among which may be mentioned magnesium and calcium chlorides.In order to keep down the cost of the composition,

it might be desirable in many instances to use such commercial salt inpreference to the chemically pure varietya Thus, it will be appreciatedthat the graphite, in addition to its function as a lubricant, willinhibit the rate of absorption of moisture from the air by the salt.Then, again, the graphite, by lubricating each grain of salt, highlydecreases intergranular friction resulting in a free-fiowing'and highlymobile mass.

While sodium chloride is preferable in the composition, it will beunderstood that other alkali metallic salts may be employed, such aspotassium and lithium chlorides. the alkali earth metallic chloridesmight be found useful. Also, in certain rare instances, substitutesmight be found for the pitch among which may be mentioned rosin or othersimilar materials having a high melting point.

Under certain conditions it might be found advantageous or desirable toomit the graphite and it is within the scope of-this invention to dothis.

The advantages of the composition forming the subject matter of thisinvention, it is believed, will now be readily apparent. .While thecomposition and the proportions of its various in- In some instances,even,

gradients have been set out in detail, it will be understood that slightvariations within the teachings of the instant disclosure may be madeand it is contemplated to cover all such and to be limited in thisrespect only as may be necessary by the scope of the claims heretoappended.

What we claim and desire by Letters Patent is: l. A mixture suitable foruse in extinguishing stubborn fires comprising a member from the groupconsisting of alkali metal chloride and alkaline earth metal chloride,and pitch and graphite, the chloride predominating.

2. A mixture suitable for use in extinguishing stubborn fires composedof sodium chloride, pitch and graphite, the sodium chloridepredominating.

3. A mixture suitable for use in extinguishing stubborn fires composedof the ingredients set out below in the approximate proportions byweight indicated:

Ounces Sodium chloride 'l 704 Pitch 20 Graphite- 16 ROBERT E. SARGEN'I.MATTHEW W. M. DEVITT.

